Methods for performing image processing, such as performing image sharpening and edge detection, on an original image have so far been developed.
For example, it is disclosed that, in order to perform image sharpening, a program product described in Non Patent Literature 1 performs local contrast control so as to detect and further brighten pixels on the bright side of an edge, and detect and further darken pixels on the dark side of the edge.
It is disclosed that, in a method described in Non Patent Literature 2, nonlinear processing is performed on a grayscale original image using a maximal overlap biorthogonal wavelet filterbank as a mathematical model for human early visual information processing.
As methods for edge detection, methods of simple filtering and methods of using wavelets have so far been well known (see Non Patent Literature 6 and 7).